The present invention relates to a linear motion device. Linear motion devices are known, e.g., as bearing rail guides or roller rail guides, in which case the first assembly is the guide carriage, and the second assembly is the guide rail. However, the present invention is also usable in linear modules, in which a linear guide having an assigned drive device is integrated to form one assembly. Potential applications also include rolling-element screw drives, in which the first assembly is formed by the nut, and the second assembly is formed by the threaded spindle.
U.S. Pat. No. 5,193,914 makes known a linear motion device in the form of a roller rail guide. According to FIG. 1 in U.S. Pat. No. 5,193,914, the linear motion device includes a first assembly 1 in the form of a guide carriage. The first assembly is movable longitudinally relative to a second assembly 2 in the form of a guide rail. For this purpose, four first rolling surfaces 9; 10; 11; 12 that extend in a longitudinal direction and are situated opposite second rolling surfaces 5; 6; 7; 8 on the second assembly are provided on the first assembly. A row of roller-shaped rolling elements that may circulate endlessly in the first assembly and in the guide carriage is situated between the aforementioned rolling surfaces. Four return passages 15; 17; 20; 21 are provided in the first assembly for this purpose.
The first assembly includes a first body, on each of the two longitudinal end faces of which a deflection assembly is provided, it being possible to install the deflection assemblies as a whole. According to FIGS. 6 and 7 of U.S. Pat. No. 5,193,914, four curved deflection passages 14; 16; 18; 19 that connect the first rolling surfaces to the assigned return passages are provided in each deflection assembly 13, thereby producing an endless circulation path. To ensure that the deflection passages are oriented toward the return passages substantially projection-free, projections 62 that engage in the return passage are provided on the return assemblies. For this purpose, a recess that is bounded by surfaces 39; 40, as shown in FIG. 3, is provided in return tube 70, in which the corresponding return passage is formed.
The disadvantage of U.S. Pat. No. 5,193,914 is that a tolerance-related offset between the deflection passage and the return passage may only be compensated for within narrow limits. The greatest permissible offset results from the play between the rolling body and the deflection passage and the return passage. This problem is particularly critical when a plurality of rolling element circuits is used since proper orientation must exist at every rolling element circuit. Particularly great tolerances must be provided for linear motion devices in which the first body is composed of aluminum, and in which the return passage is manufactured via extrusion and is formed completely and directly on the first body. In the sense of the present application, the return passage is formed completely on the first body when the latter completely encloses the return passage. It does not matter whether this condition is met along the entire length of the return passage, in particularly at its ends. The latter embodiment described above is particularly cost-favorable and is therefore used particularly preferably together with the present invention.